She seems to spend like $400-$500 a week on junk, which doesn't even include what would be considered necessities like food, rent, utilities, etc. Your hunch that something isn't adding up is mine as well. This is not a woman concerned with inconvenient things like budgeting. Also, when you consider the costs of a total hysterectomy, hospitalization, lab tests, follow-up appointments, and no real insurance, she has to be drowning in medical debt right now because there's no way she can afford this life, even if we were being generous and giving her the top number shown on Social Blade (which has been discussed before, and is more accurately somewhere in the middle for most Youtubers.)
She is still vastly overpaid at $3.5-4K a month, but she could probably get by making minimum payments, covering only essentials and not eating takeout 14 times a week and buying $40 dresses shirts that don't even fit. She's not doing that. I know there's a whole other thread devoted to her finances, so I won't get off-topic too much, but my theory is that she fully plans on filing for bankruptcy at some point. It's her 'Get out of Jail Free' card that she's holding onto until the last possible moment when her health is so poor, she can't upload anymore. And by then, she may have a legitimate claim for disability, so she won't be living large, but she won't starve either.
You can still have no job and live pretty comfortably at 650+ lbs. in the U.S. Just look at Life by Jen. No job, fat as fuck, still can afford frivolous things like monthly subscription boxes. She can even ask Alexa the weather any time of day. These whales always wax poetic about thin privilege, but what about fat privilege? They seem to get a lot of shit for free, on account of never putting the fork down.
Until that day arrives, Amber lives by the white trash motto that if you got it, spend it because it might be gone tomorrow.
In a morbid sense, I also believe people like Amber don't want to live long, don't expect to live long and so they don't plan for it. If you know you're probably untangling from this mortal coil before 50, there's no point in saving for some distant future you'll never see. Retirement is for responsible fuckers that contributed to society over a set period of time, and eventually expect to enjoy the fruits of their labor (or at least not saddle loved ones with massive amounts of debt if they check out early).